The key difference between volatile and nonvolatile is that the volatile substances have a tendency to vaporize whereas the nonvolatile substances do not have a tendency to vaporize.
Conversion from a liquid phase to the gaseous phase can take place in different paths like evaporation or vaporization at the boiling point. Evaporation is the process of changing a liquid into its vapour stage. The substances that can undergo this vaporization easily are “volatile substances”. Therefore, the term volatile refers to the ability to convert into the vapour phase. In contrast , nonvolatile substances are the opposite of the volatile substances.
What is Volatile?
Volatility is the tendency of a substance to vaporize. Volatile substances have the capability to go into the vapour phase. This may happen during heating or without heating. Volatility and the vapour pressure of a substance related to each other. If the volatility is high, the vapour pressure is also high. On the other hand, if the volatility is low, then the vapour pressure is low.
Normally liquids are volatile. They tend to go into the vapour phase rapidly. For example, acetone, hexane, chloroform are volatile liquids, which evaporates rapidly. Moreover, there are some solids which can go directly into the vapour phase without going through the liquid phase. We call this sublimation.
What is Nonvolatile?
Nonvolatile substances are substances which do not vaporize rapidly. They don’t have a higher vapour pressure at the normal room temperature and pressure. Also, nonvolatile substances will mostly exist as solids in the room temperature. For example, sodium chloride, silver nitrate are nonvolatile compounds.
Moreover, when nonvolatile compounds mix with volatile liquids such as water, it is easy to separate them by evaporation. Then the volatile liquid will evaporate leaving the nonvolatile solid at the bottom of the container.
What is the Difference Between Volatile and Nonvolatile?
The two terms volatile and nonvolatile have opposite meanings. Therefore, the key difference between volatile and nonvolatile is that the volatile substances have a tendency to vaporize whereas the nonvolatile substances do not have a tendency to vaporize. Moreover, volatile substances have a high vapour pressure at room temperature and pressure while nonvolatile substances have a low vapour pressure comparatively. Another difference between volatile and nonvolatile is that when we heat or store volatile liquids in an open container, the volume of it decreases whereas this does not happen with nonvolatile liquids.
The below infographic presents a more detailed view of the difference between volatile and nonvolatile substances.
Summary – Volatile vs Nonvolatile
In summary, volatile and nonvolatile are two terms explaining the ability of a substance to undergo vaporization easily at normal temperature and pressure conditions. Therefore, the key difference between volatile and nonvolatile is that the volatile substances have a tendency to vaporize whereas the nonvolatile substances do not have a tendency to vaporize.
1. “Volatility (Chemistry).” Wikipedia, Wikimedia Foundation, 6 Sept. 2018. Available here